Passenger ships are equipped with lifeboats and life rafts. The lifeboats and life rafts are intended to be emergency boats for carrying the persons on the passenger ship should it have catastrophic failure. While the number of spaces in the lifeboats and life rafts is sufficient for the number of persons on the passenger ship, there is the organizational problem of getting the people to the lifeboats and life rafts. There are lifeboat drills, and the passengers are instructed as to what actions to take should an emergency occur. The passengers are instructed to don their flotation devices in the form of life jackets and report to a specific lifeboat station. Such lifeboat drills are usually successful. However, should an actual emergency occur, it is quite possible that some of the lifeboats and life rafts are unuseable. It is also possible that, in the confusion of the emergency event, the distribution of the persons to the lifeboats and life rafts may not be optimum, and some may be overloaded.
A life jacket may hold up a person in the water, but the person must escape from the sinking ship in order to avoid being pulled down in the turbulent waters resulting from the sinking of the ship. Thus, a life jacket is not enough since a certain amount of strength and knowledge about swimming is required in order to save oneself.